Reversing mechanism for electric motors.



H. STEINHART. REVERSING MECHANISM FOR ELEGTRIC MOTORS.

APPLICATION FILED JUNE 4,1914.

1,1 33,675. Patented Mar. 30, 1915.

M/ITIJEEEEE INJEQTU and then connect them in reverse order.

UNITED STATES PATENT OFFICE.

HERMANN STEINHART, OF STUTTGART, GERMANY, ASSIGNOR TO THE FIRM 0F ROBERTBOSCH, OF STUTTGART, GERMANY, A CORPORATION OF GERMANY.

Specification of Letters Patent.

Patented Mar. 30, 1915.

Application filed June 4, 1914. Serial N 0. 842,818.

To all whom it may concern:

Be it known -that I, HERMANN STEINHART, a. subject of the Emperor ofGermany,-residing at and whose post-office address is Lerchenstrasse 74, Stuttgart, Germany, have invented certain new and useful Improvementsin Reversing Mechanism for Electric Motors; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as Wlll enable others skilled in the art to which it appertains, tomake and use the same.

The object of the present invention is to provide a mechanism forreversing the direction of rotation of an electric motor of the seriestype having one brushper pole and having one terminal grounded. Priorarrangements for this purpose are cumbersome in that themeans forchanging the connections of the armature circuit relatively to the fieldcircuit to reverse the motor, 1nvolve considerable manipulation and someskill, as, for instance, where it is necessary to rotate the brushholders with the1r connecting leads through a polar space, or where itis necessary to disconnect the leails n accordance with my invention,the procedure for reversing the motor is s mplified and the possibilityof error is eliminated as a practical matter. In the preferredembodiment of the invention, I provide a supporting member fastened tothe frame of the motor, and on which all of the brush holders aremounted in such manner as to be insulated therefrom. One conductingmember is disengageably fastened to the brush holders of one polarityand to the field winding, but is insulated from the supporting member;while a second conducting member is disengageably fastened to the brushholders of opposite polarity and also to the supporting member to groundthat terminal of the motor. These two conducting members areinterchangeable, and the only operation required to'reverse thedirection of rotation'of the motor is to change those members inposition so that each one becomes. fastened to those brush holders whichwere previously fastened to the other one.

In the accompanying drawings, illustrating this preferred embodiment ofmy invention in application to a direct current fourpole motor, as anexample, and in which the electrical connections are indicateddiagrammatically, Figure 1 represents a side view of the motor showingreversing mechanism arranged for one direction of rotation; Fig. 2represents a similar view but showing the reversing mechanism arrangedfor the opposite direction of rotation; and Fig. 3 represents a partialsection on line 3-3 of Fig. 1.

The supporting member a of the metal is cast in one piece, and isarranged to be carried by an end frame fastened to the field structure 6at the places 0. The supporting member is provided with four screwthreaded holes a and the two diametrically-disposed slots as shown. Thepairs of brush holders (Z (Z and e 6 are mounted on the supportingmember a, but are insulated therefrom by the insulation f, the brushesIt being held against the commutator m by spring fingers such as Z shownin Fig. l.

In Fig. 1, the brush holders (5,, d, are of positive polarity and arefastened by screws to the bar 9 of metal, which is insulated from thesupporting member by the sleeve 8 of insulating material. The conductor9 connects a terminal of a series field winding p to the bar and thus tothe two brushes is in the brush holders d 5 The bar it of metal isfastened by screws to the negative brush holders 6,, e, and is alsofastened in the diametrically-disposed slot of the supporting member aby the screws 2', thereby grounding these brushes on the frame of themachine. In Fig. 2, the bars 9 and 7 are interchanged, the brush holdersc and a, then being connected by conductor 9 and bar 9 to the fieldwinding and being-insulated from the supporting member a, whereas thebrush holders 'd, and d, are grounded on the supporting member a by thebar it fastened thereto.

In Fig. 1, the current flows from a source of current, as the battery 0,through the series field winding [7 of the motor and the conductor 9 tothe insulated conducting member 9, from which the current enters thearmature winding at the positive brushes in the brush holders d d Thecurrent leaves the armature Winding through the brushes into negativebrush holders e c and passes through the bar It into the groundedsupporting member a which is electrically connected to the negativeterminal of the battery. When current .For motors of more thanfourp'oles, the

brush holders of like polarity, are, in accordance with this invention,electrically connected by a group of rails instead of a single rail, orby any othersuitable conducting member.

Having thus described invention, WhatI claim is: I

1. In a multipolar'motor of the series type, a reversing mechanismcomprising a plurality of'insul'ated brush holders equal in number tothe number of poles in the motor, an insulated conducting memberelectrically connected to the brush holders of one polarity, and agroundedconducting member electrically connected tothe brush holders ofopposite polarity, said conducting members being interchangeable toreverse the direction of rotation of the motor. 2. In a multipolar motorof the series type, a reversing mechanismv comprising a groundedsupporting member, a plurality Qbf brush holders supported by butinsulated the supporting member and being equal in number to the numberof poles in the motor, a conducting member electrically connectedto thebrush holders of one polar ity and insulated from the supporting member,and asecon'd conducting member electrically connected to the brushholders of opposite polarity and to the supporting membeigfsaid;conducting members being interchangeable to reverse the direction ofrotation of the motor. 3. In a =multipolarmotor of the series type, areversing mechanism comprising. a grounded supporting member, aplurality of brush holders supported by but insulated from thesupporting member and being equal in number to the number of poles inthemotor, a conducting member electrically connected to thebrushrholders of one polar- 'ity by disengageable fastening devices andalso being electrically connected to one terminal of the field Winding,but being insulated from the supporting member, and a.

second conducting member electrically com nected by disengageablefastening devices to the brush holders of' opposite polarity and also tothe supporting member, said conducting members being interchangeable. toreverse the direction of rotation of the motor.

In testimony whereof I afiix my ture, in presence of two Witnesses.

HERMANN STEINHART.

Witnesses:

PAUL VVOLFART,

REINHOLD ELWERT.

signa-

